The best magazine
Abstract and Introduction
Abstract
Background Accurate tools for the noninvasive detection of hepatic steatosis are needed. The Controlled Attenuation Parameter (CAP) specifically targets liver steatosis using a process based on transient elastography.
Methods Patients with chronic liver disease and body mass index (BMI) ≥28 kg/m underwent biopsy and liver stiffness measurement (LSM) with simultaneous CAP determination using the FibroScan® M probe. The performance of the CAP for diagnosing steatosis compared with biopsy was assessed using areas under receiver operating characteristic curves (AUROC).
Results A total of 153 patients were included: 69% were male, median BMI was 32 kg/m; 47% had nonalcoholic fatty liver disease (NAFLD); and 65% had significant (≥10%) steatosis. The CAP was significantly correlated with the percentage of steatosis (ρ = 0.47) and steatosis grade (ρ = 0.51; both P < 0.00005). The median CAP was higher among patients with significant steatosis (317 [IQR 284–339] vs. 250 [227–279] dB/m with <10% steatosis; P < 0.0005) and the AUROC for this outcome was 0.81 (95% CI 0.74–0.88). At a cut-off of 283 dB/m, the CAP was 76% sensitive, 79% specific, and had positive and negative predictive values of 87% and 64%, respectively. CAP performance was not influenced by measurement variability, but was higher in patients with mild (F0-F1) fibrosis (AUROC 0.89 vs. 0.72 with F2-F4; P = 0.03). The AUROCs of the CAP for ≥5%, >33% and >66% steatosis were 0.79, 0.76 and 0.70, respectively.
Conclusions The CAP is a promising tool for the noninvasive detection of hepatic steatosis. Advantages of CAP include its ease of measurement, operator-independence and simultaneous availability with LSM for fibrosis assessment.
Introduction
Hepatic steatosis is a common histological feature among patients with the metabolic syndrome, alcohol abuse, hepatitis C virus (HCV) infection and exposure to certain medications (e.g. corticosteroids, amiodarone). The most common condition, nonalcoholic fatty liver disease (NAFLD), affects up to 30% of the population in Western countries and its prevalence is increasing. The spectrum of NAFLD ranges from simple steatosis, to steatohepatitis (NASH), advanced fibrosis including cirrhosis and end-stage liver disease. In patients with other liver disorders including HCV, coexistent steatosis may accelerate fibrosis progression and reduce treatment response. Therefore, the ability to accurately diagnose hepatic steatosis is important for clinical decision-making and estimating prognosis.
The current gold standard for evaluating steatosis and other histological lesions is liver biopsy. However, this procedure is invasive, costly, and prone to sampling error, variability in pathological interpretation and potentially serious complicatons. Moreover, repetition of liver biopsy to monitor changes in steatosis is difficult. In light of these obstacles, various noninvasive methods have been developed for the assessment of hepatic histology, particularly fibrosis. Steatosis can also be diagnosed by noninvasive means, typically with radiographic techniques (e.g. ultrasound, computed tomography [CT] and magnetic resonance imaging [MRI]). Unfortunately these tools are limited by, in some cases, high cost, restricted availability, operator dependence and poor sensitivity. Moreover, existing methods cannot simultaneously assess hepatic fibrosis and steatosis. To overcome these limitations, a novel technology based on the properties of ultrasonic signals acquired by the FibroScan® (Echosens, Paris, France) has been developed. This tool, referred to as the Controlled Attenuation Parameter (CAP), measures the degree of ultrasound attenuation by hepatic fat at the central frequency of the FibroScan® M probe simultaneously with liver stiffness measurement (LSM). In a preliminary study of 115 patients with various liver disorders, Sasso reported that the CAP was highly correlated with steatosis and had excellent diagnostic performance for grading steatosis severity.
The objective of this study was to validate the diagnostic performance of CAP for the detection and quantification of steatosis. Our study cohort included overweight and obese patients who have a high prevalence of this histological lesion.
Source: ...